Interaction behaviour of road users; Phase 1. Development of a method to determine ‘Situation Awareness' The development of a method to measure Situation Awareness is the first phase of long-term research in the field of telematics. It is important that drivers observe a traffic situation properly and also interpret its changes correctly. This in order to accurately foresee how the situation will develop in the near future. If telematic aids are to offer support, they must adapt their operation to this process. From the road safety point of view, the ultimate goal of the long-term research is, to determine criteria for telematic aids that support drivers in carrying out their driving task. Attention here is particularly directed at the secondary road network. On these roads there is frequent interaction between road users, and it usually has a complex nature. In terms of accidents, intersections deserve particular attention. Research into human abilities to observe situations accurately and to foresee and predict their development is called ‘Situation Awareness' (SA). Different methods to determine SA have been developed. They are, however, not specifically aimed at carrying out steering tasks in traffic. That is why, first of all, a method had to be developed with which the SA of road users, while carrying out their steering tasks in traffic, can be measured. With this in mind, a simulator-experiment was carried out as a pilot study. In this, three measurement methods were tested. During a ‘journey' in a simulator along a route involving a variety of traffic situations, the picture was frozen a number of times at set locations (‘freezing'). Immediately after each frozen picture, subjects from three different groups were asked to either answer a structured questionnaire or describe the situation in their own words; or draw a sketch of the situation. The result of this experiment showed that none of these methods leads individually to a usable reproduction of the traffic situation. However, the hybrid form of the sketch-drawing with additional specific questioning of subjects seems to be a useful course to continue on, especially concerning the manoeuvre features of other road users. The research will be continued in this direction. At the same time we will try to link to a study of scenarios used by drivers when settling their mutual encounters at intersections.